1. Field of the Invention
The present invention relates to a tissue retractor, especially a flexible tissue retractor used as an endoscopic device that is passed through a working channel of a flexible endoscope. The tissue retractor has application in endoscopic and open surgery, including flexible endoscopy, laparoscopy, and general surgery. It can be made rigid or flexible and in lengths and, diameters to suit the requirements of the surgical field. The flexible endoscopic tissue retractor is used to hold gastrointestinal tissue so that it can be retracted or manipulated in some way. The tissue retractor can be configured to allow grasping of specific layers of the gastrointestinal wall by adjusting the shape and/or length of the needles and their exit points at the tip of the device. For example it can be configured to grasp through the mucosal layer, and into the muscular layer, thus providing a more secure connection to the tissue and allowing manipulation of the entire thickness of the tissue. Alternately, it can be configured to grasp the mucosal layer allowing manipulation of the mucosal layer only.
2. Description of Related Prior Art
A number of conventional devices exist in the prior art, which devices are used to manipulate the tissue during the endoscopic surgical procedure for treatment of Gastroesophageal Reflux Disease (GERD).
For example, U.S. Pat. No. 6,494,888 B1 to Laufer et al. (referred to hereinafter as “Laufer”) describes an instrument for reconfiguring stomach tissue. A tissue manipulator 700 includes an elongated cable assembly 716 and a distal end effector 718 actuated by the cable assembly 716 to perform various steps in the tissue reconfiguring procedure. See Laufer at FIGS. 9A to 9F. The end effector 718 has two jaw members 720, 722 that engage tissue, in particular, tissue at the gastroesophageal junction (GEJ). During the process of implanting the two-part fastener 732, 734 (see Laufer at FIG. 8), a coil 740 is rotated into the GEJ tissue and, after being screwed therein to a sufficient extent, is used to pull the GEJ tissue between the opening defined by the two jaw members 720, 722 in an open position illustrated, for example, in FIGS. 9D and 9E. The coil tissue puller 740, 741, 742 is shown, in particular, in FIG. 3D. The puller has certain disadvantages, however. The coil 740 can penetrate too far, causing possible negative consequences if the stomach is entirely breached (through the mucosa, muscularis, and serosa layers). Because the aorta, liver, diaphragm and other vital organs are disposed adjacent to the fundus of the stomach, if the coil 740 passes through the serosa, there is a significant chance of damage to the vital organs. Also, upon withdrawal, the coil 740, due to its inherent shape, can become stuck in the tissue and, thereby, cause damage to the tissue when the user must forcefully retract the entire assembly 718. Depending on the angle of entry, it is possible that the coil 740 only enters the mucosa.
If this occurs, because the mucosa is a relatively thin, loosely attached layer, there is a high probability that the fastener 732, 734 will be only implanted in the mucosa and, therefore, result in a failed implantation procedure. Also, for fasteners that coil into the tissue, the tissue is compressed disadvantageously because rotation of the coil can twist the tissue as the coil is threaded in, which twisting can damage the tissue and cause it to weaken. Also, to advance the coil into the tissue, the coil must be rotated. It is inherently more difficult to transmit torque through a slender flexible device than it is to transmit thrust loads, thus, pushing the needles into the tissue is a more reliable actuation measure than twisting the coil into the tissue. Also, because the forces applied to the tissue by the engaging point of the device is not accompanied by an opposite reacting force of another engaging point of the device, all reaction forces must be provided through the shaft of the device.
A common general flexible endoscopic tissue grasper is most widely used today for manipulating gastrointestinal tissue (for example, one that is made by the Olympus company under the name Olympus Grasping Forceps (Catalog Number FG-49L-1)). A drawback to the Olympus grasper is its inability to reliably grasp muscularis through the mucosal layer. Another drawback is the requirement to maintain pressure on the handle while grasping the tissue. This ties up the user's hands and could lead to inadvertent release of the tissue.
The prior art devices are not constructed to easily, securely, selectively, and precisely engage the tissue during the surgical procedure.